The present invention relates to liquid oven cleaners. It is particularly useful as a composition for oven cleaners of the spread-on type as opposed to the aerosol type.
Typical prior art oven cleaners use a soluble hydroxide, usually sodium hydroxide, as a strong cleaning agent combined with starch as a thickener and water. Miscellaneous agents such as surfactants are also added. The water and starch interplay to give the composition spreadability, and yet give it sufficient body or consistency that it tends to stick to the surface on which it is applied. The mixture should be smooth and viscosities of from around 17,500 to around 75,000 cps, as determined on a Brookfield viscometer at about 70.degree. F are desirable. Compositions with viscosities above about 120,000 cps are too thick.
In aerosol compositions, soap is sometimes substituted for starch, since soap is a foam stabilizing agent (see U.S. Pat. No. 3,779,933 to Howard L. Eisen entitled "Alkaline Oven Cleaning Composition"). In the case of some spread-on oven cleaners, magnesium aluminum silicate has been substituted for flour or starch as the thickening agent (see U.S. Pat. No. 3,808,051 to Schoenholz et al entitled "Cleaning Method and Compositions" and U.S. Pat. No. 3,658,711 to Mukai entitled "Caustic Alkali-Free Oven Cleaning Composition"). In one paint removing compound, not an oven cleaner, a calcium soap has been used as a thickening agent instead of flour or starch (see U.S. Pat. No. 3,179,597 to Mankowich entitled "Vertical Adherent Paint Remover Composition").
A stroll through the neighborhood supermarket will reveal that most oven-cleaning compositions made pursuant to the prior art are merchandised in glass or metal containers. While plastic containers have been utilized to package almost every conceivable household liquid, the advantages of plastic containers have never been successfully utilized to package oven cleaners. The reason for this is that the oven cleaning compositions deteriorate considerably more rapidly when stored in plastic containers. The compositions become slimy and watery whereas in glass or metal containers, they remain relatively stable at least for substantially longer periods of time.
Heretofore, those skilled in the oven cleaning art have been unable to formulate oven cleaning compositions capable of being merchandised in plastic containers, without a resultant product degradation.